COVID Herd Immunity, Health Care Capacity, and the Risk of COVID during Air Travel

A trustworthy update on the science, and the future of the coronavirus pandemic, What should people do?

By Mark D. Harris

Three major issues are in the news recently about COVID. The first involves the possibility of herd immunity to the virus. The second is whether the US health care system will be overwhelmed. The third discusses the likelihood of SARS-COV2 transmission during air travel, especially pertinent during the holiday season. Scientists practicing science are generally reliable, but scientists practicing politics generally are not. Furthermore, the media should be acknowledged but never trusted. Here is some information you can rely on.

COVID Herd Immunity

The coronavirus pandemic has taken a heavy toll on the world, including America. From 21 Jan 2020 to 18 Dec 2020, the US had nearly 17,000,000 cases and 310,000 deaths.[1] These numbers suggest a gross (unadjusted) case fatality rate of 1.8%, frighteningly high. However, many COVID cases are asymptomatic or have mild symptoms that go unreported and undiagnosed. In June 2020 the CDC looked at COVID antibody testing and suggested that there may be ten times as many cases as detected on antigen tests, which today gives us the number 17 million.[2] The ratio of ten real cases per one laboratory confirmed case is consistent with other highly infectious aerosol diseases such as influenza. If this 10:1 ratio is accurate, at least 170,000,000 million Americans, about half of the US population, has had COVID, and the vast majority of those are probably immune to the coronavirus. If we have actually had 170 million cases instead of 17 million, the infection fatality rate is 0.18%, comparable to influenza.

The herd immunity threshold for influenza is 70-80%, which means that if 80 out of 100 Americans get the flu shot, the 20 who did not will be largely protected because of the people who did get the shot.[3]  Eighty percent is the highest credible estimate of the herd immunity threshold for the coronavirus. If so, America is almost two-thirds of the way to herd immunity even without the vaccine. With the current surge in cases, the total number of those infected is rising fast. The coronavirus vaccine is an important development that will help protect those most at risk. Even if the ratio of actual cases to laboratory confirmed cases is 8:1, at least 136 million Americans have had COVID and are largely immune. This natural immunity, combined with the targeted protection that the vaccine provides to our most vulnerable, should give us a waning pandemic by the spring of 2021.

COVID and US Health Care Capacity

COVID is a significant health problem in the US and throughout the world. However, despite media reports, COVID is not about to overwhelm the US health care system, specifically regarding hospitalization, as many panicky media outlets have claimed. According to, on 1 Jan 2021, about 18% of staffed hospital beds nationwide contained COVID patients.[4] While significant, 82% of US hospital beds are available for patients with other problems, including influenza, pneumonia, sepsis, diabetes, heart failure, post-operative care, and the legions of other reasons why people are hospitalized. While individual hospitals and certain regions can be overwhelmed, the system has the capacity to care for these patients elsewhere. For example, if a hospital in downtown Los Angeles is overwhelmed, patients can be transferred to other hospitals in LA, or to those further out in LA, Orange, Riverside, Ventura, Kern, or even San Bernardino Counties. Epidemics run in waves, and not every area is equally affected at the same time.  Though costs and reimbursement will change, and people may receive care farther from their homes and families, the patient will still receive needed care.

Risks of COVID transmission during Air Travel

Hundreds of thousands of Americans are traveling this holiday season, and not a few are worried about the risk of becoming infected with SARS-COV2 while flying. The Journal of the American Medical Society (JAMA) provides an answer.[5] While staying home may be the safest bet, the infection risk during air travel is less than that at an office building, a classroom, a supermarket, or a commuter train. Aircraft are cleaner than many other environments and the airflow in modern airliners is engineered to clean and recirculate air and minimize mixing between passengers. These airflow rates are also faster than those in buildings, washing out contaminants.

Passengers can reduce their risk further by wearing masks, staying six feet apart from others, and washing their hands. If you want to know how much immunity you have, get an antibody test.


COVID is a major threat across the world today, similar to but far less deadly than the Spanish Influenza of 1918. By and large, science and government are working together to address the risk. Many governments have grossly overstepped their authority, and citizens who love democracy, especially in the US, will have to claw back their rights. However, COVID, like all other pandemics, will recede. SARS-COV2 will fade into the background as natural herd immunity, and to a lesser extent, vaccine-related immunity, protects more and more people. The US health care and hospital systems have not been and will not be overwhelmed.

Every event in history produces a new normal, and COVID is again no exception. But the future is bright. The economy will recover, our society will adapt, and the perfect work of the Lord will be done. Though 2020 has been full of storms, our future remains bright.





[4] Estimated Inpatient Beds Occupied by COVID-19 Patients by State Timeseries, last modified 3 Jan 2021,{}.

[5] Risk of COVID During Air Travel, JAMA, November 3, 2020. Vol 324, Number 17

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